1. The Field of the Invention
The present invention relates to belts for treadmills and, more specifically, cushioned treadmill belts.
2. The Relevant Technology
Treadmills have long been a favorite stationary means for exercising. A typical treadmill comprises an elongated base having a plurality of rollers formed thereon. A continuous treadmill belt longitudinally encircles the base resting on the rollers. Handrails project upward from the front of the base for stabilizing a user on the treadmill. During operation, the user selectively grips the handrails and begins to walk or run on the treadmill belt. The treadmill belt can be either motorized or rotate under the force of the user. In either case, the treadmill belt rotates on the rollers in a continuous circular fashion as the user runs or walks on the treadmill belt. This process continues until the user obtains a desired level of exercise.
One of the critical features in the manufacture of a treadmill is the treadmill belt. Initially, the belt must be sufficiently strong to resist the impact and shearing forces which are applied to the belt as the user moves thereon. Likewise the belt must be sufficiently flexible to continually bend in a relatively flat loop without fatigue or failure. To obtain these properties, treadmill belts are commonly made from durable woven fabric. Woven fabric, however, is subject to localization displacement at the point where the foot of a user impacts the belt. That is, since the woven fabric is made of individual fibers, select fibers move relative to other fibers as a result of the force applied by the user's foot. This localized displacement can make the user's footing unstable.
An additional problem with conventional belts is that although the material may be strong enough to withstand the forces applied by the user, it can be difficult to attach the ends of the material to make a continuous loop. Stitching the ends together is often inadequate. Furthermore, making a stitched seam horizontally across the belt produces a large bump which can detrimentally effect the ride of the belt on the rollers.
Conventional treadmill belts can also be jarring to the legs of a user. To provide belts that have the necessary strength to withstand running or jogging thereon, conventional belts are made from relatively dense strong materials. Such materials, however, provide little or no cushion for absorbing the impact of the runner. Although attempts have been made to produce cushioned treadmill belts, effective belts which can withstand the required impact and stresses and yet provide cushioning have not been produced.